The invention relates to the classification of pictures by size.
During photofinishing of an exposed and developed strip of film containing a series of frames or exposures, the frames are successively scanned pointwise by an optoelectronic scanner. The scanner yields density values which are used to print the frames on copy material or to reproduce the frames on another medium, e.g., a photo CD.
A strip of film sometimes has frames of different sizes. For instance, cameras capable of producing so-called panoramic views have recently come on the market. Although these cameras use conventional 135 mm film, portions of the film along the top and bottom longitudinal edges are covered during a panoramic exposure. The length of the resulting frame is the same as that for a normal, full-size frame but the length-to-width ratio is different. As a rule, panoramic frames are printed at a greater magnification than full-size frames. The magnification is such that the width of a panoramic picture equals the width of a conventional picture.
Magnification of a panoramic picture increases not only the width but also the length of the picture. In order to print the entire picture, it then becomes necessary to expose a greater length of copy material. Accordingly, a print of a panoramic picture has the usual width but a distinctly greater length. This yields a panoramic effect.
The recently introduced cameras for taking panoramic exposures are also able to selectively produce normal, full-size exposures. Hence, film exposed in such a camera can have a mixture of panoramic and full-size exposures.
During photofinishing of a film of this type, the frames need to be printed at different magnifications and with different lengths of copy material. This makes it necessary to automatically distinguish between panoramic frames and normal, full-size frames.
A method of distinguishing between panoramic and full-size frames is disclosed in U.S. Pat. No. 5,289,229. In this method, a frame is classified as panoramic when portions of the film adjoining the upper and lower edges have a substantially uniform density while the density in the central portion of the film varies. On the other hand, when the densities in the upper and lower portions of the film vary significantly, the corresponding frame is classified as a full-size frame.
In a camera capable of taking both panoramic and full-size pictures, it is frequently possible to make an exposure, e.g., of a date, in a portion of the film which is covered when a panoramic picture is taken. Consequently, a significant density difference exists in this portion of the film thereby causing a panoramic frame to be classified as a full-size frame.
In many of the cameras designed for panoramic as well as full-size pictures, the mask which covers the upper and lower portions of the film during a panoramic exposure has openings. Such openings can be formed, for example, by the tools employed in making the cameras. Again, the openings can result in exposures on the covered portions of the film thus causing improper classification of panoramic frames.